Breast Health

Raloxifene May Help Lower the Risk of Invasive Breast Cancer

A medication already approved to reduce the risk of breast cancer in high-risk women also appears to cut the risk for other women, says a report in the Journal of the National Cancer Institute.

A new analysis finds that those who took raloxifene (Evista®) regularly over a number of years were less likely to develop invasive estrogen-receptor (ER) positive breast cancer, compared with women who did not take the medication.

Raloxifene, a selective estrogen receptor modulator, or SERM, did not cut the risk for noninvasive breast cancer or invasive ER-negative cancers.

Noninvasive cancers confine themselves to the ducts or lobules and do not spread to the surrounding tissues in the breast or other parts of the body.

They can, however, develop into or raise the risk for a more serious, invasive cancer. Invasive cancers are more aggressive and have started to break through normal breast tissue barriers and invade surrounding areas.

Medication Blocks Estrogen Cancers

Dr. Elizabeth Barrett-Connor, at the University of California San Diego, explains, "This research gives older women facing certain medical decisions another option."

"For example, if a woman at risk for osteoporosis is considering taking medication, and has no history of blood clots or stroke, raloxifene might be a more appealing option due to its protective role in invasive breast cancer," she says.

Dr. Barrett-Connor was principal investigator of the RUTH (Raloxifene Use for the Heart) trial, originally designed to see if raloxifene, which has cholesterol-lowering properties, could reduce the risk of dying from coronary heart disease.

Breast cancer is the most common cancer among women. According to the American Cancer Society (ACS), 182,460 new cases of female breast cancer will be diagnosed in 2008 and 40,480 women will die due to breast cancer.

SERMs block the female hormone estrogen by binding to estrogen receptors; estrogen helps fuel the growth of some breast cancers.

Raloxifene was originally developed to prevent and treat osteoporosis, and only later was found to help reduce the risk of invasive breast cancer in high-risk women.

The new study expands on the original results of the RUTH trial, which involved more than 10,000 postmenopausal women with coronary heart disease or at risk for the condition. Participants were randomly chosen to receive either daily raloxifene or a placebo and followed for an average of 5.6 years.

Raloxifene turned out not to have any effect on heart disease risk of death, but it did reduce the risk of invasive breast cancer by 44 percent, which translates into 1.2 women per 1,000 treated for one year who were spared the agony of a breast cancer diagnosis.

The new analysis looked more specifically at raloxifene's effect on breast cancer and found a 55 percent lower incidence of invasive ER-positive tumors, but no effect on noninvasive breast cancer or invasive ER-negative breast cancer.

High-Risk Group Defined

According to the study authors, these findings are consistent with results from other clinical trials involving women without heart disease.

This clinical trial and others found an increased risk of blood clots and fatal strokes among women taking raloxifene, indicating that women need to weigh the risks and benefits of the medication.

Another question is how long to take raloxifene for breast cancer prevention, although the authors suggest that up to eight years might be safe and effective.

Researchers say women who would have the best risk-benefit ratio would be those at high risk of breast cancer, who have a 30 to 50 percent chance of getting breast cancer in the next five to 10 years, and low risk of venous thrombosis and stroke. A reduced risk of spine fractures would be an additional benefit.

"This is a reaffirmation that the drug raloxifene is very powerful for reducing the risk of invasive breast cancer," says Dr. Jay Brooks, at Ochsner Health System in Baton Rouge, Louisiana.

September 2008

Study of Tamoxifen and Raloxifene

The Study of Tamoxifen and Raloxifene, or STAR, is a clinical trial that began at an estimated 500 sites across the US and Canada early in 1999.

Participants in STAR included more than 19,000 postmenopausal women who are at increased risk for breast cancer. They received a medication that could reduce their chances of developing breast cancer.

STAR built upon the success of the Breast Cancer Prevention Trial (BCPT), which showed that high-risk women taking the drug tamoxifen for an average of four years had a 49 percent reduced chance of developing breast cancer.

Results from STAR determined whether raloxifene (Evista®), a medication similar to tamoxifen, was as effective as tamoxifen in reducing the chance of developing breast cancer in women who have not had the disease, and whether the medication had benefits over tamoxifen (Nolvadex®), such as fewer side effects.

Raloxifene was approved by the US Food and Drug Administration (FDA) as an osteoporosis prevention drug for postmenopausal women.

Women chosen to participate in STAR were age 35 or older, postmenopausal, and had an increased risk of breast cancer as determined by their: age, family history of breast cancer, personal medical history, age at first menstrual period, and age at first live birth.

They were randomly assigned to receive either tamoxifen daily or raloxifene daily for five years.

They received close follow-up examinations, including mammograms, physical examinations, and gynecologic examinations, on a regular basis for at least seven years.

The National Surgical Adjuvant Breast and Bowel Project (NSABP), which conducted the trial, selected the 193 main institutions to participate in STAR, including sites in 48 states, six Canadian provinces, the District of Columbia, and Puerto Rico.

These 193 institutions have formed networks with other local physicians, creating an estimated 400 active centers participating in the trial.

STAR began enrolling participants in 1999 and concluded in 2006.

The results of the STAR trial produced evidence that regular use of raloxifene works as well as tamoxifen at reducing breast cancer risk in post-menopausal women who are at high risk, but appears less likely to cause some of the potentially dangerous side effects seen with tamoxifen use, such as an increase in uterine cancer and blood clots in the lungs and major veins.

Always consult your physician for more information.

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